Researchers have developed a novel power generation system that uses the friction generated as everyday water moves in and out of precisely engineered nanometer-sized pores in silicon monoliths to produce a surprising amount of usable electricity.
Scientists have previously developed extremely small electrical energy generators that use mechanical or friction energy, called triboelectric nanogenerators (TENGs). These include devices that generate energy from raindrops, human sweat, and even the well-known drinking bird toy. Still, those devices have often converted a very small percentage of the mechanical energy needed to drive their reactions. This limited efficiency has slowed, or even prevented, their adoption beyond the laboratory setting.
The research team from Deutsches Elektronen-Synchrotron (DESY) and Hamburg University of Technology (TUHH) behind the newly announced water-powered TENG said their silicon monoliths, designed with precision nanopores, showed a 9% energy conversion rate, which “ranks among the highest ever reported for solid–liquid nanogenerators.”
“Even pure water, when confined at the nanoscale, can enable energy conversion,” explained Patrick Huber, spokesperson of the BlueMat – Water-Driven Materials Excellence Cluster at the Hamburg University of Technology (TUHH) and DESY.
In a statement announcing the device’s invention, the researchers explain that their particular TENG works by capturing the electricity generated at the interface between the material and the liquid. Specifically, this occurs when water is forced under pressure in and out of the pores on the surface of the silicon monoliths. Described as an Intrusion–Extrusion Triboelectric Nanogenerator (IE-TENG), the researchers compared the electricity generated by the friction between water and the silicon pores to that generated when one walks across a PVC carpet.
“Electrons transfer from one body to another, accumulating a charge that is suddenly discharged when a third body is touched,” they explain. “For example, when touching a door handle, the charge flows away, and you get a small electric shock.”
Study co-author Luis Bartolomé from CIC energiGUNE noted that, along with its energy conversion efficiency, one of the main benefits of the team’s approach is its reproducibility. The researcher said that’s because their system operates without rare or exotic materials, “but just by using the most abundant semiconductor on earth, silicon, and the most abundant liquid, water.”
Manuel Brinker from the Hamburg University of Technology said one “crucial step” was developing precisely engineered silicon structures that are conductive, nanoporous, and also hydrophobic.
“This architecture allows us to control the motion of water inside the pores — making the energy conversion process both stable and scalable,” Brinker explained.
While some materials and structures might offer one or two of those properties, finding a material design that has all three, is cost-effective, efficient, and scalable was difficult. Still, the researchers accomplished the feat with their final design.
The co-authors suggest that devices based on their design could efficiently power water-detection systems, smart garments that monitor biometric data, and advanced athletic performance sensors. They also state that their device could also be adapted to haptic robotics, “where touch or motion directly generates an electrical signal.
“Water-driven materials mark the beginning of a new generation of self-sustaining technologies,” added corresponding authors Simone Meloni from the University of Ferrara and Yaroslav Grosu from CIC energiGUNE.
The study “Triboelectrification during non-wetting liquids intrusion–extrusion in hydrophobic nanoporous silicon monoliths” was published in Nano Energy.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.